1. Field of the Invention
The present invention relates to a method of making a semiconductor chip out of a wafer as a bulk of semiconductor chips, and to a method of mounting a semiconductor chip onto a printed circuit board or substrate.
2. Description of the Prior Art
A semiconductor chip such as an integrated circuit (IC) is in general cut out of a silicon wafer. The cut out semiconductor chip is then mounted onto a printed circuit board. When the semiconductor chip is mounted in this manner, input/output bumps on the semiconductor chip is received on the surface of a substrate of the printed circuit board. The input/output bumps serve to establish an electric connection between the semiconductor chip and the printed circuit board.
An underfill material is filled in a space between the semiconductor chip and the substrate of the printed circuit board. The underfill material serves not only to prevent any deterioration such as corrosion of the input/output bumps but also to reinforce the bonding between the semiconductor chip and the substrate of the printed circuit board.
In general, a dispenser is employed to supply the underfill material. The dispenser is designed to discharge the liquid of the underfill material for the individual semiconductor chips one after another. It takes a longer time to supply the underfill material to all of the semiconductor chips.
In addition, the input/output bumps are in general formed on the upward surface of the silicon wafer. The individual semiconductor chip cut out of the silicon wafer should be reversed before the semiconductor chip is actually mounted on the substrate of the printed circuit board. It also takes a longer time to reverse each of the semiconductor chips cut out of the wafer.
It is accordingly an object of the present invention to provide a method of mounting a semiconductor chip onto a printed circuit board in a shortened working time.
According to the present invention, there is provided a method of supplying an underfill material for a semiconductor chip, comprising: locating a wafer which receives a conductive bump on an upward front side; and transferring an underfill material sheet adhered to a surface of a thin film member onto the upward front side of the wafer.
The underfill material can be supplied commonly to a plurality of semiconductor chips included in the wafer in the method of supplying. Accordingly, the working time can greatly be reduced as compared with the case where the underfill material is supplied separately to the individual semiconductor chips. In particular, if the supply of the underfill material can be completed before the semiconductor chip is mounted on a printed circuit board or substrate in this manner, the method of mounting the semiconductor chip onto a printed circuit board or substrate is supposed to be facilitated.
The method of supplying may further comprise: urging the underfill material sheet onto the upward front side of the wafer after softening the underfill material sheet when transferring the underfill material sheet onto the wafer; and peeling the thin film member from the underfill material sheet after hardening the underfill material sheet. The transfer of the underfill sheet in this manner may be achieved prior to or after cut-out of the individual semiconductor chips.
According to a second aspect of the present invention, there is provided a method of mounting a semiconductor chip onto a printed circuit board or substrate, comprising reversing a wafer as a bulk of semiconductor chips prior to pickup of an individual semiconductor chip.
The method of mounting allows the semiconductor chips to be reversed in the block. Accordingly, the working time can greatly be reduced as compared with the case where the individual semiconductor chips are separately reversed.
According to a third aspect of the present invention, there is provided a method of mounting a semiconductor chip onto a printed circuit board or substrate, comprising: forming a conductive bump on an upward front side of a wafer; dicing the wafer on a first support member so as to cut out individual semiconductor chips; superposing a second support member over the first support member so as to hold the semiconductor chips between the first and second support members; reversing the first support member along with the second support member holding the semiconductor chips therebetween; picking up the individual semiconductor chips after removing the first support member.
The method of mounting allows the semiconductor chips, held between the first and second support members, to be reversed in the block. Accordingly, the working time can greatly be reduced as compared with the case where the individual semiconductor chips are separately reversed.
According to a fourth aspect of the present invention, there is provided a method of making a semiconductor chip, comprising: forming a conductive bump on an upward front side of a wafer; reversing the wafer; and forming a resin lamination on a backside of the wafer.
The resin lamination can be formed on the backsides of the individual semiconductor chips cut out of the wafer in the method of making. The resin lamination is allowed to hold tiny fragments, fractured out of the semiconductor chip, on the semiconductor chip. The resin lamination thus prevents a scatter or drop of the tiny fragments. The resin lamination serves to reliably suppress generation of dust resulting from the semiconductor chip to the utmost.
In providing the resin lamination, the method of making may further comprise transferring a resin sheet, adhered to a surface of a thin film member, to the backside of the wafer. This process enables a common supply of the resin lamination to a plurality of semiconductor chips included in the wafer. Accordingly, the working time can greatly be reduced as compared with the case where formation of the resin lamination is conducted separately for the individual semiconductor chips. In particular, if the supply of the resin lamination can be completed before the semiconductor chip is mounted on a printed circuit board or substrate in this manner, the method of mounting the semiconductor chip onto a printed circuit board or substrate is supposed to be facilitated.
According to a fifth aspect of the present invention, there is provided a method of making a semiconductor chip, comprising: reversing a wafer receiving a conductive bump on an upward front side; and dicing the wafer from a backside of the wafer.
When the dicing process is effected on the wafer, the individual semiconductor chips can be cut out of the wafer. The cut out semiconductor chip is then picked up, so that it can be mounted on a printed circuit board or substrate. It is not necessary to reverse the individual semiconductor chips after the dicing process in mounting the semiconductor chip onto a printed circuit board or substrate. Accordingly, the subsequent method of mounting can thus greatly be facilitated. The working time can further be shortened.
The wafer may be subjected to irradiation of an electromagnetic wave. Any metallic lamination and/or conductive bumps are in general supposed to block the transmission of the electromagnetic wave. The electromagnetic wave passing or penetrating through the wafer is allowed to reveal the position and shape of the metallic lamination and/or conductive bumps. The thus revealed positions for the metallic lamination and/or conductive bumps in this manner enable a precise and reliable determination of the cutting position in a facilitated manner without directly observing the metallic lamination and/or conductive bumps.
The method of making may further comprise: forming a nick along a contour of the semiconductor chip on the backside of the wafer. If an evaporated resin lamination is formed within the nick, a broader coverage of the evaporated resin lamination can be obtained over the surface of the resulting semiconductor chip as compared with the case where the individual semiconductor chips are simply cut out of the wafer without formation of the nick. The evaporated resin lamination is allowed to hold tiny fragments, fractured out of the semiconductor chip, on the semiconductor chip. The evaporated resin lamination thus prevents a scatter or drop of the tiny fragments. The evaporated resin lamination serves to reliably suppress generation of dust resulting from the semiconductor chip to the utmost.
When the evaporated resin lamination is allowed to remain in the nick, the method of making may further comprise cutting out an individual semiconductor chip along the nick with an incision narrower than the nick after formation of the evaporated resin lamination. The narrower incision along the nick thus serves to form a flange on the semiconductor chip adjacent the nick. The evaporated resin lamination is allowed to reliably remain in the nick except the area subjected to the incision. Accordingly, the evaporated resin lamination is allowed to reliably remain on the flange and the side of the cut out semiconductor chip. In particular, if the incision is forced to trace the centerline of the nick, the single incision leads to formation of the flanges on the adjacent semiconductor chips separated by the incision.
According to a sixth aspect of the present invention, there is provided a method of making a semiconductor chip, comprising: locating a wafer receiving a conductive bump on an upward front side; adhering an underfill material sheet onto the upward front side of the wafer; reversing the wafer; and dicing the wafer from a backside of the wafer.
The underfill material can be supplied commonly to a plurality of semiconductor chips included in the wafer in the method of making. The working time can greatly be reduced as compared with the case where the underfill material is supplied separately to the individual semiconductor chips. In addition, the method of making allows the semiconductor chips to be reversed in the block prior to the dicing process. Accordingly, the working time can further be reduced as compared with the case where the individual semiconductor chips are separately reversed. Moreover, the method of making enables elimination of reversal of the individual semiconductor chips after the dicing process, so that the subsequent method of mounting can thus greatly be facilitated. The working time can still further be shortened.
The wafer may be subjected to irradiation of an electromagnetic wave in the aforementioned manner. Also, the backside of the wafer may be subjected to formation of a nick along a contour of the semiconductor chip in the aforementioned manner. An evaporated resin lamination may likewise be formed on the backside of the wafer. Additionally, the individual semiconductor chips may be cut out of the wafer along the nick with an incision narrower than the nick after formation of the evaporated resin lamination.
According to a seventh aspect of the present invention, there is provided a semiconductor chip comprising: a conductive bump; a chip body receiving the conductive bump at a downward front side; a flange extending outward from a periphery of the chip body; and an evaporated resin lamination extending along an upward surface of the flange, the periphery of the chip body and an upward backside of the chip body.
In general, when the semiconductor chip is mounted on a printed circuit board or substrate, an underfill material is filled up within a space between the semiconductor chip and the surface of the printed circuit board or substrate. If the semiconductor chip is urged against the printed circuit board or substrate, the conductive bump is squeezed or compressed. As the conductive bump thus gets flattened or low-profiled, the underfill material is allowed to overflow out of the space defined between the semiconductor chip and the surface of the printed circuit board or substrate. The overflowing underfill material flows along the flange so as to finally reach the side or periphery of the chip body. The chip body is thus completely contained within the evaporated resin lamination and the underfill material. A complete containment of the chip body in this manner serves to hold tiny fragments, fractured out of the chip body, on the chip body. A scatter of drop of the tiny fragments can completely be prevented.
In making the semiconductor chip of the above type, a method of mounting a semiconductor chip onto a printed circuit board, may comprise: locating a wafer receiving an underfill material sheet on a downward front side receiving a conductive bump; forming a nick along a contour of the semiconductor chip on an upward backside of the wafer; forming an evaporated resin lamination on the upward backside of the wafer; and cutting out an individual semiconductor chip along the nick with an incision narrower than the nick.
An underfill material supplying film or tape may be employed to supply the underfill material sheet onto the wafer. The underfill material supplying film may comprise: a thin film tape; and an underfill material sheet superposed on a surface of the thin film tape. The contour of the underfill material sheet is allowed to reflect the shape of the wafer.
In particular, a through hole is preferably defined to continuously penetrate through the thin film tape and the underfill material sheet in the underfill material supplying tape. The through hole serves to release a gas such as an air existing in the vicinity of the conductive bump when the underfill material supplying tape is superposed on the front side of the wafer. A gas is prevented from staying between the front side of the wafer and the underfill material sheet. The underfill material sheet is allowed to reliably contact the front side of the wafer over its entire surface.
It is preferable that the location or arrangement of the through hole reflects the location or arrangement of a conductive bump received on a surface of a corresponding wafer. If the height of the conductive bump is set larger than the thickness of the underfill material sheet, the conductive bump is allowed to reliably project the tip end out of the underfill material sheet through the through hole. Exposure of the tip end of the conductive bump enables a reliable establishment of the connection between the conductive bump on the semiconductor chip and a corresponding conductive pad on a printed circuit board or substrate.
An anisotropic conductive material sheet may be employed as an underfill material sheet in the underfill material supplying film. The anisotropic conductive material sheet may include metallic particles dispersed in an insulating layer received on the surface of the thin film tape. Employment of the underfill material supplying tape of this type allows the metallic particles to be interposed between a conductive bump on a semiconductor chip and a corresponding conductive pad on a printed circuit board or substrate when the semiconductor chip is to be mounted on the printed circuit board or substrate. An electric connection can reliably be established between the conductive bump and the corresponding conductive pad. In particular, even in the case where a large number of conductive bumps are formed on the single semiconductor chip, an electric connection can reliably be established between the conductive bumps and the corresponding conductive pads, respectively.
An utter insulating layer without metallic particles may be formed to extend over the surface of the insulating layer. The utter insulating layer serves to apparently increase the thickness of the underfill material sheet including the anisotropic conductive material sheet without losing the function of the anisotropic conductive material sheet. The usage of the expensive anisotropic conductive material sheet can be reduced as compared with the case where the anisotropic conductive material sheet is solely included in the underfill material supplying film. Superposition of the utter insulating layer contributes to reduction in the production cost.
According to an eighth aspect of the present invention, there is provided a semiconductor chip mounter comprising: a platen; a bonding head opposing a chip receiving surface to the platen; and an electromagnetic wave output opening defined at the chip receiving surface of the bonding head. Here, an optical fiber guiding an infrared ray from an infrared source may expose its tip end at the electromagnetic wave output opening.
The semiconductor chip mounter may be employed to realize a method of mounting a semiconductor chip onto a printed circuit board, comprising: attaching the semiconductor chip, receiving a conductive bump embedded in an underfill material sheet, to a chip receiving surface of a bonding head; detecting the shadow of the conductive bump based on an electromagnetic wave penetrating through the semiconductor chip; and positioning the bonding head based on the shadow of the conductive bump. The method of mounting serves to reliably position the semiconductor chip relative to the printed circuit board even when the conductive bump is completely embedded within the underfill material sheet.
According to a ninth aspect of the present invention, there is provided a semiconductor chip mounter comprising: a platen; a bonding head opposing a chip receiving surface to the platen; and an irradiation source opposed to the chip receiving surface of the bonding head so as to irradiate an electromagnetic wave toward the chip receiving surface.
The semiconductor chip mounter may be employed to realize a method of mounting a semiconductor chip onto a printed circuit board, comprising: attaching the semiconductor chip, receiving a conductive bump embedded in an underfill material sheet, to a chip receiving surface of a bonding head; irradiating an electromagnetic wave toward the underfill material sheet; photographing a fluorescent light of the underfill material sheet; and positioning the bonding head based on the intensity of the fluorescent light. The method of mounting serves to reliably position the semiconductor chip relative to the printed circuit board even when the conductive bump is completely embedded within the underfill material sheet.